Ventricular tachycardia (VT) is a difficult clinical problem for the physician. Its evaluation and treatment are complicated because it often occurs in life-threatening situations that dictate rapid diagnosis and treatment. VT is defined as three or more beats of ventricular origin in succession at a rate greater than 100 beats/minute. The rhythm is frequently regular, but on occasion it may be modestly to wholly irregular. The arrhythmia may be either well-tolerated or associated with grave, life-threatening hemodynamic compromise. The hemodynamic consequences of VT depend largely on the presence or absence or myocardial dysfunction (such as might result from ischemia or infarction) and on the rate of VT.
VT can be referred to as sustained or nonsustained. Sustained VT refers to an episode that lasts at least 30 seconds and generally requires termination by antiarrhythmic drugs, antitachycardia pacing techniques or electrical cardioversion. Nonsustained VT refers to episodes that are longer than three beats but terminate spontaneously generally within 30 seconds.
Implantable cardiac rhythm management devices are an effective treatment in managing irregular cardiac rhythms in particular patients. Implantable cardiac rhythm management devices are capable of recognizing and treating arrhythmias with a variety of therapies. For the reasons stated above, and for other reasons stated below, which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for providing a method for adapting the initiation of a therapeutic therapy for those patients who experience recurring non-sustained arrhythmic episodes.